static void Main(string[] args)
        {
            string filePath = "Lorem ipsum dolor sit amet.pdf";
            //load a random document
            PdfFormatProvider provider = new PdfFormatProvider();
            RadFixedDocument originalDocument;
            using (Stream stream = File.OpenRead(filePath))
            {
                originalDocument = provider.Import(stream);
            }
            //draw something on the first page
            FixedContentEditor editor = new FixedContentEditor(originalDocument.Pages[0]);
            editor.GraphicProperties.IsFilled = true;
            editor.GraphicProperties.FillColor = RgbColors.Black;
            Telerik.Documents.Primitives.Rect Rect = new Telerik.Documents.Primitives.Rect(10, 10, 200, 100);
            editor.DrawRectangle(Rect);

            //export the pages as images and build a brand new document from the images
            SkiaImageFormatProvider imageProvider = new SkiaImageFormatProvider();
            imageProvider.ExportSettings.ImageFormat = SkiaImageFormat.Jpeg;
            imageProvider.ExportSettings.ScaleFactor = 0.8;
            imageProvider.ExportSettings.Quality = 80;


            RadFixedDocument doc = new RadFixedDocument();
            foreach (RadFixedPage page in originalDocument.Pages)
            {
                byte[] resultImage = imageProvider.Export(page);
                RadFixedPage pdfpage = doc.Pages.AddPage();
                editor = new FixedContentEditor(pdfpage);
                Stream imageStream = new MemoryStream(resultImage);
                editor.DrawImage(imageStream);
            }

            //export the pdf built from the images
            PdfFormatProvider pdfFormatProvider = new PdfFormatProvider();
            string outputPdf = @"output.pdf";
            File.Delete(outputPdf);
            using (Stream output = File.OpenWrite(outputPdf))
            {
                pdfFormatProvider.Export(doc, output);
            }
            Process.Start(new ProcessStartInfo() { FileName = outputPdf, UseShellExecute = true });
        }

        static void Main(string[] args)
        {
            string filePath = "Lorem ipsum dolor sit amet.pdf";
            //load a random document
            PdfFormatProvider provider = new PdfFormatProvider();
            RadFixedDocument originalDocument;
            using (Stream stream = File.OpenRead(filePath))
            {
                originalDocument = provider.Import(stream);
            }
            //draw something on the first page
            FixedContentEditor editor = new FixedContentEditor(originalDocument.Pages[0]);
            editor.GraphicProperties.IsFilled = true;
            editor.GraphicProperties.FillColor = RgbColors.Black;
            Telerik.Documents.Primitives.Rect Rect = new Telerik.Documents.Primitives.Rect(10, 10, 200, 100);
            editor.DrawRectangle(Rect);

            using (Stream output = File.OpenWrite(filePath))
            {
                provider.Export(originalDocument, output);
            }

            using (Stream stream = File.OpenRead(filePath))
            {
                originalDocument = provider.Import(stream);
            }
            //export the pages as images and build a brand new document from the images
            SkiaImageFormatProvider imageProvider = new SkiaImageFormatProvider();
            imageProvider.ExportSettings.ImageFormat = SkiaImageFormat.Jpeg;
            imageProvider.ExportSettings.ScaleFactor = 0.8;
            imageProvider.ExportSettings.Quality = 80;


            RadFixedDocument doc = new RadFixedDocument();
            foreach (RadFixedPage page in originalDocument.Pages)
            {
                byte[] resultImage = imageProvider.Export(page);
                RadFixedPage pdfpage = doc.Pages.AddPage();
                editor = new FixedContentEditor(pdfpage);
                Stream imageStream = new MemoryStream(resultImage);
                editor.DrawImage(imageStream);
            }

            //export the pdf built from the images
            PdfFormatProvider pdfFormatProvider = new PdfFormatProvider();
            string outputPdf = @"output.pdf";
            File.Delete(outputPdf);
            using (Stream output = File.OpenWrite(outputPdf))
            {
                pdfFormatProvider.Export(doc, output);
            }
            Process.Start(new ProcessStartInfo() { FileName = outputPdf, UseShellExecute = true });
        }

System.IO.IOException: I/O error when opening file 'C:\WINDOWS\FONTS\MSYH.TTC'.

System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.IO.IOException: I/O error when opening file 'C:\WINDOWS\FONTS\MSYH.TTC'.
   at MS.Internal.FontCache.FileMapping.OpenFile(String fileName)
   at MS.Internal.FontCache.FontSource.GetUnmanagedStream()
   at System.Windows.Media.GlyphTypeface.ComputeSubset(ICollection`1 glyphs)
   at Telerik.Windows.Documents.Fixed.Model.Fonts.CidType2Font.ComputeSubset(IEnumerable`1 usedCharacters)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontStream.CopyPropertiesFromOverride(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontStream.CopyPropertiesFrom(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontDescriptor.CreateFontFile(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontDescriptor.ExportFontFile(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.FontDescriptor.CopyPropertiesFrom(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.CidFontObject.CopyPropertiesFromOverride(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.CidFontObject.CopyPropertiesFrom(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.Fonts.Type0FontObject.CopyPropertiesFromOverride(IPdfExportContext context, FontBase font)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Export.PdfExporter.WriteFontsFromContext(PdfWriter writer, IPdfExportContext context)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Export.PdfExporter.Export(IRadFixedDocumentExportContext context, Stream output)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.PdfFormatProvider.ExportOverride(RadFixedDocument document, Stream output)
   at Telerik.Windows.Documents.Common.FormatProviders.FormatProviderBase`1.Export(T document, Stream output)